As an exhaust gas purification apparatus for purifying exhaust gas of a diesel engine, an exhaust gas purification apparatus provided with a DPF (Diesel Particulate Filter) is known. In this type of exhaust gas purification apparatus, soot which is particulate matter (PM) contained in the exhaust gas, is collected by the DPF and then exhausted.
The DPF allows limited accumulation amount of soot collected therein. Thus, when there is too much soot accumulated in the DPF, normally an automatic regeneration or a manual regeneration is performed to prevent so-called “over-accumulation state”. More specifically, when the soot is accumulated in the DPF more than a certain amount, an engine control unit (ECU) automatically performs the regeneration (operation-period regeneration) in the automatic regeneration or, a user is notified of a regeneration timing by a means such as a lighting/flashing means and then performs the regeneration through a switch operation or the like in the manual regeneration.
Although the above automatic regeneration or the manual regeneration is performed, the DPF remains in the over-accumulation state in some cases. In such case, the output of the engine is reduced and the regeneration is prohibited in a limp home mode. In such case, the vehicle installed with the above engine, is taken to a service deposit such as a dealer and a repair factory to reset the engine from the above state. In the service deposit, the DPF in the over-accumulation state is removed from the engine and cleaned or replaced to cancel the over-accumulation state.
In the case where the DPF is in the over-accumulation state, as for an on-road vehicle which is made for driving on a general road, the vehicle can be moved or transported easily to the service deposit. However, as for an industrial vehicle which is not made for driving on a general road, it is difficult to move or transport the vehicle to the service deposit. This is due to the fact that such industrial vehicles are subjected to restrictions such as the limited number of service deposits, limited service space and restricted moving method.
As a technique to regenerate the DPF, disclosed in Patent Literatures 1 and 2 is how to decide a regeneration temperature and a regeneration timing in accordance with the PM accumulation amount of the DPF.
As a technique to solve the over-accumulation state of the DPF, disclosed in Patent Literature 3 is how to control an operation method so as to produce required torque without increasing the PM in such a case that the DPF becomes in the over-accumulation state and the engine is in the limp home mode.
Further, disclosed in Patent Literature 4 is a technique to regenerate the DPF by combusting the PM accumulated in the DPF through controlling of an electric heating means and an air supply means in the case where the DPF is in the over-accumulation state.